Lost hotspots and passive female preference: the dynamic process of lek formation in capercaillie Tetrao urogallus
2000
Gjerde, Ivar | Wegge, Per | Rolstad, J⊘rund
The evolutionary processes behind the polygynous mating system known as leks are difficult to document. One approach is to study the behaviour that drives the formation of new leks today. Several hypotheses have been put forward to explain the formation of leks, and they can roughly be divided into two groups; one which advocates that the males are the driving force and one which argues that the females are the driving force. In this study we use data from a long‐term study (1979–1998) of a capercaillie population at Varaldskogen in southeast Norway to develop a model describing how new leks are formed in this species. By using data on spacing pattern and behaviour of radio‐marked young and adult birds of both sexes we demonstrate how the situation develops from winter towards mating in spring. Furthermore, we report on a few cases of new leks that have arisen in the area during the 20 years of study. We argue that both female mate choice, male territoriality and male attraction to locations with high densities of females are involved in a dynamic process of lek formation. We present results which indicate that new leks are mainly founded by young birds. Finally, we show that when new leks are formed the spacing patterns of the individuals involved change. This questions the method of using comparisons between the position of female home ranges and established leks to infer how leks are formed.
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